Isn’t being a child enough??

My in-laws have this idea that our 4-yr old should be active during her waking hours! She’s in daycare from 9am-2pm and when she gets home, most days she wants her downtime, usually she plays with her dollhouse or watches her favorite series. I explained to them once, she’s half her day in daycare and with a lot of other kids and people around her with plenty of activities. Their nap time is 30min-1hr. She goes to gym once a week and we do plenty walks or take her everywhere with me. I don’t want to be that parent overloading with activities and classes. She’s 4, she gets to be a child not for long. In 2 years she’ll be going to school. Why are some adults so eager to push small kids into a lot activities?